The subject matter disclosed herein generally relates to automated industrial systems, and more specifically, to generating a load path for an automated industrial system.
Some automated industrial systems (e.g., turbine systems) include a compressor, a combustor, a turbine, and an exhaust system. The compressor compresses air from an air intake, and subsequently directs the compressed air to the combustor. In the combustor, the compressed air received from the compressor is mixed with a fuel and is combusted to create combustion gases. The combustion gases are directed into the turbine. In the turbine, the combustion gases flow against and around turbine blades of the turbine, thereby driving rotation of the turbine and any external load. The external load may include an electrical generator. Some embodiments of automated industrial systems include combined cycle systems. Combined cycle systems include exhaust systems that have a heat recovery steam generator (HRSG). An HRSG improves the efficiency of the automated industrial system by using excess heat energy that passes through the turbine in exhaust to generate additional power.
Automated industrial systems may be operated at base load (e.g., normal power output) or at part load (e.g., lower power output relative to the base load). The transition from base load to a part load is considered a load path. A method of lowering power output includes first reducing airflow through an inlet which causes the temperature in the exhaust to increase. As the exhaust temperature increases, the HRSG steam is attemperated (e.g., liquid is mixed in to reduce temperature) to limit the maximum temperature of the steam. However, attemperation causes the automated industrial system efficiency to decrease because excess heat energy is dissipated without using the energy. Additionally, some embodiments of the described load path results in the highest possible turbine operating temperatures and hence part life of various components of the automated industrial system is reduced.